The present invention relates to a method for manufacturing a shoe, and to a shoe obtained with such method.
Conventional sports shoes, for example for mountaineering, are produced by using a nonrigid sock to which an upper, open at the bottom, is coupled perimetrically and in an upward region by stitching. The upper is in fact subsequently placed at a last, and its ends are turned over on an adapted insole and are stitched or glued thereto to obtain a closed configuration that is adapted to fully surround the nonrigid sock. A sole provided with a tread is then coupled below the upper by injection-molding or stitching.
EP 0 152 783 discloses a flat sole that has a box-like shape in the region of the toe and a counter in the heel region; these parts are connected by lateral walls and the sole comprises selective support means that are associated with the sole and are adapted to vary its flexibility. The sole and its components are then stitched or glued to the upper.
U.S. Pat. No. 4,706,316 discloses a method for producing shoes that entails, in this case too, the production of separate components that can be mutually associated to obtain the upper, to which a sole is subsequently glued.
Both of the described solutions in any case have a member that is provided with counters for the heel and for the toe and is stitched or glued to the upper together with the other components of the shoe.
This conventional method allows a simplified assembly, because the unit constituted by the member and by the nonrigid sock acts as a semifinished item on which various components are then fitted. Several manual stages are, however, still required.
This conventional method also entails stitches or gluing operations for mutually associating the various components.
Furthermore, the manual nature of the described operations does not ensure constant quality of the finished product, since this depends on the skill of the operator.
It is also noted that the external stitches considerably reduce the waterproofing of the shoe.
Furthermore, the cost of the assembly operations is high, and this accordingly causes a high cost of the finished product.
FR-2208279 discloses a method for manufacturing a shoe including molding a plastic material on a semifinished item constituted by an upper connected to a sole member. A problem connected with this method is that the upper has to be firmly associated with the sole member before molding.
Conventional skates are constituted by a cuff rotably associated with a shell, both made of plastics. A soft innerboot is arranged inside the shell and the cuff and a pivoting frame for the wheels, arranged for example in an in-line fashion, is associated with the shell.
The method for manufacturing these products substantially entails molding the shell and the quarter, connecting them, and then inserting the soft innerboot inside them.
DE-3,043,425 discloses a skate which is substantially composed of three separate bodies: a frame adapted to support wheels or an ice-skating blade, a soft innerboot and a rigid insole.
The insole is provided, in the lower part, with adapted pins which, once associated with the innerboot and with the frame, allow the rigid interconnection of the three components of the skate.
The use of this conventional method to fix the innerboot to the frame necessarily requires the presence of a rigid structure, constituted by the insole, inside the innerboot, and this component makes direct contact with the foot.
This hinders the user's comfort as well as the stability of the foot inside the innerboot.
It has in fact been noted that the rigid insole must be formed according to a standard foot shape and therefore cannot optimally adapt to the specific shape of each individual user.
It is also noted that due to the stresses applied during sports practice, the pins are subject to deformations that alter the connection to the other two bodies that compose the skate.
Accordingly, a decrease occurs in the control sensitivity of skate on the part of the user, in the stability of the skate itself, and ultimately also in the safety of the skater.
CA-2,071,806 discloses a shoe for a skate with in-line wheels, comprising a shell that only partially surrounds part of the soft innerboot.
The shape of the shell is such as to substantially have lateral containment regions at the toe and heel of the innerboot and only to a very limited extent on the sides of the foot; this solution allows to extract the soft innerboot while the foot is still inserted therein and is indeed allowed by the limited containment of the innerboot in the middle lateral region.
However, this solution entails drawbacks: the shell thus shaped in fact does not ensure securing of the soft innerboot to the shell, because of the limited number of securing points.
The innerboot can thus move inside the shell and tends to move both longitudinally to the skate and transversely thereto.
These relative movements cannot be compensated by tightening the levers further; therefore, there is a real possibility that the innerboot might slip out of the shell during skating, with conceivable severe consequences for the user.
The relative movements of the soft innerboot inside the shell in any case entail further disadvantages, such as less control and maneuverability of the sports implement, worsened as regards the insufficient lateral containment provided by the shell when the skater performs lateral thrusts to increase his speed or when the brakes with the method known as "side-slip", which entails placing the skate in a direction that is approximately perpendicular to the direction of travel.
CA-2,101,718, filed by Canstar Sports Group Inc., discloses a partial solution to these drawbacks; the patent relates to a skate with in-line wheels the frame whereof is associated to a shell partially surrounding a soft innerboot, said shell having a front toe cup, which partially surrounds the toe of the shoe, and perimetric guiding seats for a first strap that surrounds the upper part of the foot, compressing it, and for a second strap that surrounds the foot instep.
Although these straps allow to retain the innerboot in the shell, preventing its escape, they do not fully eliminate the problem of the relative movements between the two components. Furthermore, the effect of the straps is that the foot is compressed against the bottom of the shell, without being able to make the innerboot optimally adhere laterally to the shell.
During sports practice, the stresses acting on the shell are countless and have different characteristics; accordingly, the user is forced to tighten the strap considerably, but excessively tight closure causes discomfort to the user's foot, such as painful regions where the strap applies its pressure or difficult blood circulation in the foot, because of excessive pressure on the foot.
The only remedy is to avoid tightening the straps too much, but in this case the problem of not having good securing of the innerboot to the shell remains.
WO-95/03101 discloses a shoe for a skate with in-line wheels comprising a shell that only partially surrounds a soft innerboot, which is fixed to the shell by gluing.
A quarter is articulated to the shell and has flaps that surround the tibial region and secure the innerboot by means of an appropriate lever; the shell is laterally provided with two seats for guiding a strap that affects the foot instep region.
This solution, however, also entails drawbacks, such as the industrialization of the step for gluing the innerboot, which is very difficult because of the shapes of the shells to which the innerboot must be glued.
Furthermore, gluing entails imperfect finishing due to the possible presence of smears and smudges of glue on the innerboot along the perimeter of the shell, thus worsening its aesthetic appearance. Furthermore, in the case of production rejects, both the innerboot and the shell cannot be recovered.
Finally, during sports practice the foot tends to move inside the innerboot due to the applied forces; the continuous actions of compression and traction forces entail the gradual separation of the innerboot from the shell, thus causing the innerboot to perform unwanted movements, with a gradual decrease in skate control.